1. Field of the Invention
This invention relates to the manufacture of water-insoluble heavy metal soaps or metallic soaps and, more particularly, it relates to the manufacture of those metallic soaps which, in their molten state, are pourable liquids. It is therefore chiefly concerned with the soaps of cadmium, cobalt, lead, manganese, copper and zinc.
2. Description of the Prior Art
Metallic soaps have found wide application in industry, for example, as waterproofing agents, thickening and suspending agents, and as lubricants; they are also employed in cosmetics, lacquers, plastics, in powder metallurgy, as mold release agents, flattening agents, fillers, anti-foaming agents and driers in paints, and in tablet manufacture. They are also used as heat and light stabilizers for plastics, especially polyvinyl chloride. The most common metallic soaps are those prepared from calcium, zinc, magnesium, barium and aluminum.
The heavy metal or metallic soaps have conventionally been prepared from the metal oxides or metal salts and aliphatic carboxylic acids, particularly the higher fatty acids containing from about 12 to 22 carbon atoms, which acids are known and sold to the industry as commercial fatty acids. The commercial fatty acids as commonly used are usually mixtures of higher fatty acids in which the name attached to them may be only the dominant acid of the mixture. In some grades of commercial stearic acid, however, the dominant fatty acid is not stearic acid but another fatty acid, for example, palmitic acid.
The three basic methods conventionally employed for the manufacture of metallic soaps are described in U.S. Pat. No. 2,890,232, Russell H. Rogers, Jr. et al, issued June 9, 1959 and U.S. Pat. No. 3,803,188, Leonard Frank Scott et al, issued Apr. 9, 1974. The manufacture of metallic soaps is also described in U.S. Pat. Nos. 2,945,051, Gerald M. Davis, issued July 12, 1960 and 2,650,932, Leonard M. Kebrich et al, issued Sept. 1, 1953.
Metallic soaps of the higher fatty acids, the most common of which are the metallic stearates derived from commercial grades of stearic acid, are prepared by two principal methods: